Fennel Tatin. Preheat the oven to 425°F (220°C, Gas Mark 7). Heat the oil in a pan, then gently sweat the fennel and onion until they are softened but not browned. Add the orange zest, juice and garlic; season to taste. Add enough water to cover the fennel. Cook on a medium high heat until the water has completely evaporated and the fennel becomes soft. Meanwhile, make the pesto by combining all the ingredients together in a bowl. Season to taste and set aside. Add the coriander to the fennel and carefully stir in. Drizzle over the honey and allow it to caramelize slightly in the pan, then remove from heat. Generously butter a 9-10-in (22-25 cm) pie dish. Drizzle with the balsamic vinegar and sprinkle with sugar. Arrange the pieces of fennel in the dish, cover with the puff pastry, then prick with a fork. Trim away the excess pastry allowing a rim of 1-in (2.5 cm), then tuck snuggly around the fennel inside the dish. Cook for 30 minutes in the oven, until the pastry has risen and is firm and golden. Remove from the oven and invert plate over top and turn out the tart. Drizzle the cilantro pesto over top and serve.
Coriander Pesto: Combine all the ingredients together in a bowl. Season to taste and set aside.
